1. Field of the Invention
The present invention relates to a hatch cover and especially a hatch cover for effectively closing and fluid sealing a hatch opening in a ship and analogous vessels.
2. Description of the Prior Art
Existing hatch covers for the hatch openings in ships are unsatisfactory because typically they do not effectively seal the hatch opening against the flow of fluid therethrough after repeated operation of the hatch-latching mechanism.
Additionally, the latching mechanisms of existing hatch covers typically employ some sort of screw action to clamp the cover tightly against the rim of the hatch opening. The screw threads of such mechanisms are subject to corrosion from exposure to salt water and are difficult or impossible to operate when corroded.
Moreover, the handles used to activate the latching mechanism of typical hatch covers must usually be removed from the cover when not in use and stored elsewhere because otherwise it would project above the surface of the hatch cover and deck and could trip someone unaware of its presence. Such separate handles are peculiarly subject to being lost or misplaced, further complicating and delaying the hatch opening and closing procedure.
Furthermore, the latching mechanisms of existing hatch covers are typically unnecessarily complex, having numerous moving parts and depending on close tolerances between such parts for their successful operation. Such mechanisms are particularly subject to malfunction when fouled by corrosion or when worn.
The most common prior hatch covers have also encountered sealing problems because of the nature of the seal employed and because sealing pressure has been applied at only two points about the perimeter of the cover.
Many prior hatch covers also have latching mechanisms which obstruct the hatch opening when the cover is removed from the opening.
Hatch covers and analogous closures illustrative of the known state of the art and of the foregoing problems are disclosed in the following U.S. Pat. Nos. 1,204,221; 1,416,308; 1,458,391; 1,659,202; 2,283,371; 2,327,716; 2,408,733; 2,447,464; 2,470,776; 2,488,524; 2,546,760; 3,155,052; and 3,821,935.
In view of the foregoing there is a need for an improved hatch cover which has the capability of forming a watertight seal after repeated closures, which is free of jamming and other malfunction despite long exposure to salt water, and which eliminates the problem of lost or misplaced latch-actuating handles.